Aluminum inlaid piston



Y June 1s, 1929.

D. J. CAMPBELL ALUMINUM NLAID PISTON Filed June 20, 19,27

Patented .lune 18, 1929.

PATENT OFFICE.

DONALD J. CAMPBELL, OF MUSKEGON, MICHIGAN.

ALUMINUM INLAID PISTON.

Application led .Tune 20, 1927. Serial No. 199,928.

This invention relates to a composite piston or one in which two metals are used in producing the piston, one usually being cast iron and the other aluminum. it is an object and purpose of the present invention to produce a piston wherein aluminum is used to forni the major portion of the head of the piston, being cast in such a manner in conjunction with the cast iron part of the piston that it may be said to be inlaid at the top and at the upper portions of the sides Of the piston and securely interlocked with the cast iron part and held very firmly against any possibility of disconnection or loosening.y At the same time the piston ring grooves formed in the piston are partly through the aluminum and partly through the cast iron, whereby the ring grooves are not wholly in aliminum, but being also partly in the cast iron are strengthened and reinforced against possibility of battering and widening, which occurs many times in either aluminum or composite pistons having aluminum heads in which the ring grooves are'made.

An understanding of the invention may be lhad from the following description in connection with the accompanying drawings, in which Fig. l is a plan view of the piston with a part thereof broken away and shown in section.

Fig. 2 is a vertical section through the pistEon substantially on the plane of 2-2 of ig. l.

Fig. 3 is a fragmentary side elevation of the upper end of said piston, and

Fig. l is a fragmentary vertical section onv the line .4--1 of Fig. l.

Lilie reference characters refer to like parts in the different figures of the drawings.

In the construction of the piston a skirt 1 of cast iron is made, from which integral inwardly extending bosses 2 project to serve as wrist pin bearings. Above said bosses the piston is continued and formed into a closed top 3 which, at it upper side, is provided with a plurality of radial upwardly extending ribs l extending from points near the center of said top outwardly and increasing in width as the same extend outwardly, said ribs at their outer ends joining with vertical ribs 5 at the curved outer side of the piston and which lie in the same `planes as the outer sides of the ski-rt 1. This makes grooves G at the outer vertical sides of the upper end of the' cast metal part of the piston between the ribs 5 which at their Lipper' ends join with the spaces between the top ribs ll. The ribs 4: are dovetailed in form, that is, are undercut at their sides and inner ends and, similarly, the ribs 5 are undercut as shown in Fig. l so as to be of dovetail form. In addition, at

the lower ends of the ribs 5 a groove 7 is made so that below the lower endsof said ribs 5 a continuous groove is made ventirely around the cast metal part of-the piston at its upper side joining with the vertical grooves 6 between the ribs 5, this groove, where it passes underneath the lower ends of the ribs 5 is also in dovetail form, being wider at its bottom than at its outer side.

Over the upper end of the cast metal part of the piston described, the aluminum portion of the pistonis cast so as to fill the spaces between the ribs i and 5 and fill the groove This provides a top 8 of aluminum, the upper side of which lies flush with 'the upper side of the ribs 4. Integral with this top are downwardly extending sides 9 between the ribs 5 which integrally join a ring l0 at their lower ends which extends through the groove 7 below the lower ends of the ribs 5 above a shoulder 7L formed around the cast metal part of the piston a short distance above the wristpin bearing bosses 2, said shoulder forming the lower side of the groove 7 previously described. In the aluminum sides 9 of the aluminum head thus made andin the ribs 5 of the cast iron in the head of the piston ring, piston ring grooves 11 are made, it being evident that the ring grooves are partly in the aluminum and partly in the cast iron.

The composite piston thus made of cast iron and aluminum is one wherein the aluminum is positively and securely interlocked with the cast iron part of the piston and cannot become disconnected therefrom or even loosened with respect thereto. The meltedaluminum flows into all of the recesses in the cast iron part of the piston filling the same and connecting with the dovetailed construction of the ribs 4 and 5 and the groove 7 a very secure and positive connection of the aluminum part to the cast iron part ofthe piston is made.

Aluminum being a very goodconductor of heat, better than cast iron, carries the heat absorbed by the piston from the explosions to the rings and to the walls of the cylinder. The piston is equipped with wrist pin bearing bosses of cast iron, which is very desirable and the ring grooves are partly in the cast iron which is better than to have such grooves wholly in the aluminum, because of the softer character of aluminum as compared to cast iron and its liability to batter and widen the ring grooves when the piston is in service. All of these features are present in the piston described.

It is. further apparent that the head of the cylinder is in effect two ply orlaminated.

` vThat is, there is a closed upper end of cast iron or its alloy over which is placed and permanently secured a thickness or ply of ahumv num. The aluminum is of much higher heat conductivity. Approximately it conducts heat four times faster than does the lower lamination of iron. Therefore, the heat developed by the explosion will be carried by the aluminum into the cylinder walls and into thewater circulation of the engine, while at the inside of the piston, duc to the lower con ductivity of the iron, it will be relatively cool and there will be no detrimental heating of the oil in the crank case or any carbonizing of the same at the under side of the piston head. Accordingly,I have produced a piston which, has all of the advantages of cast iron so far as the wrist pin bearings are concerned, and so far as resistance at the ring grooves to battering from the rings is concerned, while at the same time theV aluminum head in addition to lightening the weight of the piston serves as a rapid conductor of heat to the water circulation of the engine and keeps the piston below said head much cooler than if it was wholly of cast iron.

The invention is described in the appended claims and is to be considered comprehensive of all forms of structure coming within the scope of said claims.

I claim:

1. A composite piston comprising, a piston shell of cast iron, including a skirt, wrist pin bosses integral therewith and an integral top, said top and the upper portion of rthe sides of said shell having spaced ribs projecting up- Vwardly from the top and outwardly from said sides, and a head of aluminum cast over the top and the upper portions'of the sides of said shell, the upper side of the top of said head lying flush with the upper sides of the ribs on the top of said shell and the outer depending sides of the aluminum lying flush with the ribs at the sides of said shell.

2. A construction containing the elements Aincluding a skirt, wrist in combination defined in claim l, said ribs being undercut at their sides and ends so that the ribs are wider at their outer portions than where they join the shell, the aluminum lilling the recesses made by said undercuts, whereby a permanent and secure interengageinentand interlocking of the aluminum and cast iron is made. y

3. A piston comprising, a shell of cast iron pin bosses and top integral with each other, the upper end of said shell having a plurality of spaced apart ribs extending outwardly from the shell there being grooves between said ribs and said ribs at their lower ends terminating short of the skirt of said piston, whereby grooves are made between the lower ends of the ribs and the upper end of the skirt, an aluminum top for the piston over the upper end of said shell lling said grooves and extending over the top of the shell, and ring grooves around the upper end of the piston through said ribs and the sides of the aluminum head.

et. A piston construction comprising, a shell of cast metal including a skirt, wrist pin bosses and a closed upper portion of less di` ameter than the skirt formed as an integral casting, said upper end portion of the shell having radial rribs projecting upwardly from the top joining at their outer ends with depending spaced apart ribs integral with the shell extending' so as to lie in the same plane with the outer sides of the skirt,f and an aluminum head cast over the upper end portion of the shell having its upper side flush with the upper ribs and depending sides iiush with the outer sides of the side ribs of said shell, and piston ring grooves around the upper end portion of 'said piston through the side ribs of the shell and through the depending aluminum portions of theshell between said ribs.

5. A construction containing the elements in combination deiined in claim 4, said ribs having undercut sides and ends whereby the outer sides of the ribs are wider than where they join the shell and said vertical side ribs terminating at their ends short of the upper Vend of the skirt, the aluminum filling the spaces between the lower ends of the vertical side ribs and the upper end of said skirt and entering the undercut recessesof said ribs to make a firm and secure vinterlock between the aluminum head and cast iron shell y of the piston. Y

6. A piston comprising, a cylindrical inetallic shell having a portion of its periphery of reduced diameter, spaced apart longitudinal ribs extending outwardly from the reduced portion of the shell and a metal of higher heat conductivity than the shell located between said ribs in said reduced portion, the outer surface of said ribs and said metal between the ribs being shaped to conform to the outer surface of the shell.

7. A piston comprising, a Cylindrical metallic shell having a portion of its periphery of reduced diameter, spaced apart longitudinal ribs extending outwardly from the re- 5 duced portion of the shell and a metal of higher heat Conductivity than the shell located between said ribs in said reduced portion, the

outer surface of said ribs and said metal between the ribs being shaped to conform to the outer surface of the shell, and ring grooves 10 in that portion of the cylinder composed of said ribs and said metal between the ribs.

In testimony whereof I aiiX my signature.

DONALD J. CAMPBELL. 

